Switch neutron-dynamic-routing job to be non-voting temporaray

This job is now broken due to [1]. Revert for this patch is already
proposed in [2] but as this block all patches in neutron-tempest-plugin
repo, and there are in queue patches which should improve stability of
other neutron scenario jobs, lets not wait until [2] will be merged and
quickly unblock gates now.

[1] https://review.opendev.org/#/c/288271/
[2] https://review.opendev.org/#/c/691710/

Change-Id: I3951fa12a3b2c840ba2a11f22a298e7926aef649
Related-Bug: #1850626
1 file changed